The present disclosure relates to a method for designing a contact hole mask for use with a negative photoresist, and a system for effecting the same.
For printing of a two-dimensional array of contact holes, a solution for defining the image on a photoresist relies on peaks in the aerial image, which have lower contrast than valleys in the aerial image. For this reason, a positive photoresist tends to provide less resolution than a negative photoresist because the part of the aerial image having the greatest intensity contrast cannot be used to define the contact holes in the case of positive photoresists. Thus, a method for enhancing the contrast of an image for a two-dimensional array of contact holes for a negative photoresist is desired.